[From Shoujo Magic]:
A classic Saki Ohta love triangle that defies puberty! Tsugumi is sixteen years old and in love with Shougo Mizushima! He’s so handsome and popular, though, that she doesn’t think she has a chance. But not even the news that her mother has arranged a marriage for Tsugumi is enough to stop her from hoping. Having a fiancé she’s never met just means Tsugumi needs to act fast. She confesses to Mizushima that same day. But that same day, someone else confesses to Tsugumi? Who is this lusty little eleven-year-old, and how does he know Tsugumi’s name…!?
[VOL. 01: STORY 02] (English Title) Mini I Can’t Wait until Nightfall. (Japanese Title) ちょこっと夜まで待てない。 (Romaji Title) Chokotto Yoru made Matenai.